Lecture About Threats to Internal Validity

2.03 Internal Validity - Trump Video

This is a short video that President Trump released on Twitter soon after being released from the hospital when he had Covid-19. During the video President Trump makes a number of claims about a monoclonal antibody drug made by Regeneron that he received when hospitalized for Covid-19. When he made these claims about the treatment, the research about whether the treatment worked was not yet public. Furthermore, he makes a number of claims based on evidence that is subject to different threats to internal validity. So the objectives of watching this video is to identify those threats, and more broadly, to practice identifying threats to internal validity in everyday life and when being exposed to claims being made by people in society.

video
questions or see TopHat
answers

2.04 Internal Validity - Fake Article

This exercise is about identifying threats to internal validity. It includes a fake article with a series of questions in which you assess whether each type of threat could have happened, and if there is evidence that it did happen.

Assignment or see TopHat
answer key
Class Recording

2.05 Internal Validity - Depression Article

This exercise involves reading an article about CBT for depression. When reading the article, you should read the entire article to understand the methods and results, and pages 32-36 will be especially useful.

Article
Assignment or TopHat

Though I recognize that it is longer than usual for this class, I have selected it for the following reasons:

It is a classic article - it is one of the first articles on CBT
Though it is longer than most of the articles you have read for this class, it is not unusually long for psychology articles
Something unusual about it is that on pages 32-36 there is an extended discussion of the strengths and weaknesses with this article in regards to internal validity, so it is highly relevant to what we are talking about in class.

Activity Info

Objectives
- Understand a wide variety of threats to internal validity (design confounds, selection effect, order effect, carryover effect, testing/practice/fatigue effects, maturation, history, instrumentation, attrition, regression to the mean, observer bias, demand characteristic, placebo effects)
- see how researchers talk about threats and other limitations in the general discussion of an article
What Students Should Be Able To Do After This Activity
- practice identifying which threats to internal validity could have occurred based on the study design and identifying evidence of which threats actually occurred or likely occurred
Prerequisite Knowledge
- understand the different sorts of experimental designs and terms such as within vs. between subjects, counterbalancing, etc.
What Students Struggle with
- The format of the three-part questions (could threat have happened in this study, is there any evidence relevant to whether it did happen, how did the threat impact the results of the study) is hard for some students, especially understanding whether it likely exaggerated or diminished the finding. It is important to learn this way of thinking for the test.